Replacement of Replications with Additional Locations for Grain Sorghum Cultivar Evaluation
1992
Johnson, J. J. | Alldredge, J. R. | Ullrich, S. E. | Dangi, O.
Crop failure and low yields due to insufficient rainfall have led to undernutrition and starvation in West and Central Africa in recent years. Fanners have not adopted superior cultivars recommended from research station trials, necessitating on-farm testing of new cultivars under farmers' conditions. The number of test plots possible within a farmer-managed on-farm test is constrained, but the number of tests is flexible. More new cultivars could be tested in farmers' fields if replications within locations were replaced by additional locations. Improved and local cultivars of sorghum [Sorghum bicolor (L.) Moench] were tested in North Cameroon in replicated on-farm tests in 23 locations in 1987 and 60 locations in 1988. The required number of locations necessary to replace replications was examined under different probabilities of making Type I, II, and III errors and various true differences between cultivar yields for each year. Traditionally, only Type I error risk has been considered when deriving the optimum allocation of plots among replications and locations. Type III error, leading to choice of inferior cultivars, is considered the most serious risk. Results indicated that simultaneous control of Type I and Type III errors would require two to three times the number of locations as required for control of Type I error alone. Three-replicate tests can be replaced by 42 to 65% additional single-replicate locations and triple the number of cultivars tested annually in farmers' fields. WSU Departmental Paper no. 9001-48.
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